Illumination apparatus, illumination method, exposure apparatus, and device manufacturing method

ABSTRACT

To optionally forming a multilevel light intensity distribution on an illumination pupil plane, the illumination apparatus implements Köller illumination on an illumination target surface, using as a light source the light intensity distribution formed on the illumination pupil plane on the basis of light from a light source. The illumination apparatus has a spatial light modulator, a condensing optical system, and a controller. The spatial light modulator has reflecting surfaces which are two-dimensionally arranged and postures of which can be controlled independently of each other. The condensing optical system condenses light from the reflecting surfaces to form a predetermined light intensity distribution on the illumination pupil plane. The controller controls the number of reflecting surfaces contributing to arriving light, for each of points on the illumination pupil plane forming the light intensity distribution, according to a light intensity distribution to be formed on the illumination pupil plane.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a Continuation of U.S. application Ser. No.14/664,576 filed Mar. 20, 2015, which is a Continuation of applicationSer. No. 12/256,055 filed Oct. 22, 2008, which is based upon and claimsthe benefit of priority (priorities) from Provisional Application No.60/996,295 filed Nov. 9, 2007 and Japanese Patent Application No.2007-287987 filed Nov. 6, 2007, the entire contents of the priorapplications being incorporated herein by reference.

BACKGROUND OF THE INVENTION

Field of the Invention

An embodiment of the present invention relates to an illuminationapparatus incorporating a spatial modulation unit for generating apredetermined light intensity distribution (pupil luminancedistribution) on an illumination pupil plane on the basis of light froma light source, an illumination method using the spatial modulationunit, an exposure apparatus incorporating the illumination apparatus,and a device manufacturing method using the exposure apparatus.

Related Background Art

A reflection-type spatial light modulator is hitherto known as a spatialmodulator to form a pupil luminance distribution for modifiedillumination (e.g., a dipolar, quadrupolar, or other distribution) inexposure apparatus. Such a reflection-type spatial light modulator isdescribed, for example, in Japanese Patent Application Laid-open No.2002-353105 (Document 1).

There is also a recent trend to demand multilevel (3- or more-valued)distributions rather than a simple binary (presence/absence of light)distribution, as pupil luminance distributions for modified or off-axisillumination (e.g., cf. Patent Document 2: U.S. Pat. No. 6,466,304). InDocument 2, a multilevel pupil luminance distribution is obtained byplacing a spatial filter with a number of transparent regions composedof a semitransparent substrate and a masking film, in the illuminationpupil plane.

SUMMARY OF THE INVENTION

The inventor studied the foregoing conventional technology and found thefollowing problem.

Specifically, the above-cited Document 1 discloses nothing aboutformation of the multilevel pupil luminance distribution. Since thetechnology in the above-cited Document 2 uses the spatial filter toobtain the multilevel pupil luminance distribution, it fails to obtain amultilevel pupil luminance distribution in which luminances (lightintensities) in respective zones on the illumination pupil plane areoptionally controlled.

An embodiment of the present invention has been accomplished in order tosolve the problem as described above, and provides an illuminationapparatus and illumination method with a structure capable of forming amultilevel pupil luminance distribution in which luminances inrespective zones on the illumination pupil plane are optionallycontrolled, and to provide an exposure apparatus incorporating theillumination apparatus and a device manufacturing method using theexposure apparatus.

An embodiment of the present invention provides an illuminationapparatus and illumination method which are configured to form apredetermined light intensity distribution on an illumination pupilplane on the basis of light from a light source, and to implement Köhlerillumination on an illumination target surface using the predeterminedlight intensity distribution as a light source.

In order to achieve the above object, an embodiment of the presentinvention provides an illumination apparatus which comprises a spatiallight modulator, a condensing optical system, and a control unit. Thespatial light modulator has a plurality of reflecting surfaces whosepostures are controlled independently of each other. These reflectingsurfaces are two-dimensionally arranged on an optical path of lighttraveling from a light source to an illumination pupil plane. Thecondensing optical system are arranged in a light path of light from thereflecting surfaces of the spatial light modulator to form apredetermined light intensity distribution on the illumination pupilplane. The condensing optical system condenses light from the reflectingsurfaces of the spatial light modulator to form a predetermined lightintensity distribution on the illumination pupil plane. The control unitfeeds a control signal to the spatial light modulator in accordance witha light intensity distribution to be formed on the illumination pupilplane.

Particularly, in an embodiment of the illumination apparatus, thecondensing optical system converts light provided with a predeterminedangle distribution by the reflecting surfaces of the spatial lightmodulator, into a position distribution on the illumination pupil plane.The control unit controls a number of the reflecting surfacescontributing to arriving light, for each of points on the illuminationpupil plane constituting the light intensity distribution.

An embodiment of the present invention provides an illumination methodwhich comprises arrangement of a plurality of reflecting surfaces,arrangement of a condensing optical system, and posture control of thereflecting surfaces. The postures of the respective reflecting surfacesare controlled independently of each other and the reflecting surfacesare two-dimensionally arranged on an optical path of light travelingfrom a light source to an illumination pupil plane. The condensingoptical system is arranged on an optical path of light traveling fromthe reflecting surfaces to the illumination pupil plane and functions toconvert light provided with a predetermined angle distribution by thereflecting surfaces, into a position distribution on the illuminationpupil plane. The posture control of the reflecting surfaces comprisesfirst controlling a number of the reflecting surfaces contributing toarriving light, for each of points on the illumination pupil planeconstituting the light intensity distribution, when the predeterminedlight intensity distribution is formed on the illumination pupil planeby condensing the light from the reflecting surfaces by the condensingoptical system. The posture control is carried out for each group ofreflecting surfaces controlled in this manner.

An embodiment of the present invention provides an exposure apparatuswhich comprises the illumination apparatus with the structure asdescribed above (an embodiment of the illumination apparatus accordingto the present invention) for illuminating a predetermined pattern, andperforms exposure of the predetermined pattern on a photosensitivesubstrate.

An embodiment of the present invention provides a device manufacturingmethod which is to manufacture a desired device, using the exposureapparatus with the structure as described above (an embodiment of theexposure apparatus according to the present invention). Specifically,the device manufacturing method comprises an exposure block, adevelopment block, and a processing block. The exposure block is toeffect the exposure of the predetermined pattern on the photosensitivesubstrate, using the exposure apparatus with the structure as describedabove. The development block is to develop the photosensitive substrateonto which the predetermined pattern has been transferred, andthereafter to form a mask layer in a shape corresponding to thepredetermined pattern on a surface of the photosensitive substrate. Theprocessing block is to process the surface of the photosensitivesubstrate through the mask layer.

BRIEF DESCRIPTION OF THE DRAWINGS

A general architecture that implements the various features of theinvention will now be described with reference to the drawings. Thedrawings and the associated descriptions are provided to illustrateembodiments of the invention and not to limit the scope of theinvention.

FIG. 1 is a drawing schematically showing a configuration of theexposure apparatus according to an embodiment of the present invention;

FIG. 2 is an optical path diagram showing arrangement of a spatial lightmodulator and a condensing optical system, as a major part of theillumination apparatus and illumination method according to anembodiment of the present invention;

FIGS. 3A to 3D are drawings schematically showing a configuration of thespatial light modulator shown in FIG. 2;

FIG. 4 is a drawing for explaining an example of grouping of a pluralityof mirror elements in the spatial light modulator shown in FIG. 2;

FIGS. 5A and 5B are drawings for schematically explaining anotherexample of a technique to control a pupil intensity distribution on amultilevel basis;

FIG. 6 is a flowchart for explaining manufacturing blocks ofsemiconductor devices, as the device manufacturing method according toan embodiment of the present invention; and

FIG. 7 is a flowchart for explaining manufacturing blocks of a liquidcrystal device such as a liquid crystal display device, as the devicemanufacturing method according to another embodiment of the presentinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the following, embodiments of the illumination apparatus,illumination method, exposure apparatus, and device manufacturing methodaccording to the present invention will be described below in detailwith reference to FIGS. 1 to 3, 3A to 3D, 4, 5A, 5B and 6 to 7. In thedescription of the drawings, the same portions and the same elementswill be denoted by the same reference symbols, without redundantdescription.

FIG. 1 is a drawing schematically showing a configuration of theexposure apparatus according to an embodiment of the present invention.In FIG. 1, the Z-axis is set along a direction of a normal to a wafer Wbeing a photosensitive substrate, the Y-axis along a direction parallelto the plane of FIG. 1 in a plane of the wafer W, and the X-axis along adirection normal to the plane of FIG. 1 in the plane of the wafer W.

Referring to FIG. 1, the exposure apparatus EA has an illuminationapparatus IL, a mask stage MS supporting a mask M, a projection opticalsystem PL, and a wafer stage WS supporting the wafer W. The illuminationapparatus IL has a light source 1 and a spatial light modulation unit 3arranged in the order named along the optical axis AX of the exposureapparatus EA. The exposure apparatus EA is configured to illuminate themask M by means of the illumination apparatus IL on the basis of lightfrom the light source 1 and to project an image of a surface with apattern thereon (first surface) of the mask M, onto a surface on thewafer W (second surface) by means of the projection optical system PL.The illumination apparatus IL, which illuminates the surface with thepattern thereon (first surface) of the mask M with the light suppliedfrom the light source 1, implements modified illumination (off-axisillumination), e.g., dipole, quadrupole, or other illumination by meansof the spatial light modulation unit 3.

The illumination apparatus IL has a polarization control unit 2, aspatial light modulation unit 3, a zoom optical system 4, a fly's eyelens 5, a condenser optical system 6, an illumination field stop (maskblind) 7, and a field stop imaging optical system 8 along the opticalaxis AX.

The spatial light modulation unit 3 forms a desired pupil luminancedistribution (pupil intensity distribution) in its far field (Fraunhoferdiffraction region), based on the light from the light source 1 havingtraveled through the polarization control unit 2. A spatial lightmodulator 3 a of the spatial light modulation unit 3 is composed of alarge number of mirror elements as described below, and the illuminationapparatus IL also has a control unit 10 which outputs a control signalfor controlling inclinations of these mirror elements, to the spatiallight modulator 3 a.

The polarization control unit 2 is disclosed, for example, in U.S.Patent Published Application No. 2006/0055834A1. The teachings of theU.S. Patent Published Application No. 2006/0055834A1 are incorporated byreference.

The fly's eye lens 5 divides the wavefront of incident light and forms asecondary light source consisting of light source images as many as lenselements thereof on the rear focal plane of the fly's eye lens 5. Thefly's eye lens 5 applicable herein is, for example, a cylindrical microfly's eye lens. Such a cylindrical micro fly's eye lens is disclosed,for example, in U.S. Pat. No. 6,913,373. The teachings of the U.S. Pat.No. 6,913,373 are incorporated by reference.

In the exposure apparatus EA of the present embodiment, the mask Mdisposed on an illumination target surface is subjected to Köhlerillumination, using the secondary light source formed by the fly's eyelens 5, as a light source. Therefore, the plane where this secondarylight source is formed becomes a plane conjugate with an aperture stopof the projection optical system PL and thus can be called anillumination pupil plane of the illumination apparatus IL. Typically,the illumination target surface (the surface where the mask M isarranged or the surface where the wafer W is arranged) becomes anoptical Fourier transform surface with respect to the illumination pupilplane.

The pupil luminance distribution (which is also referred to as a pupilintensity distribution) is a light intensity distribution on theillumination pupil plane of the illumination apparatus IL or on a planeconjugate with the illumination pupil plane. However, when the number ofwavefront divisions by the fly's eye lens 5 is large, there is a highcorrelation between the global light intensity distribution formed onthe entrance plane of the fly's eye lens 5 and the global lightintensity distribution of the entire secondary light source, and,therefore, the light intensity distributions on the entrance plane ofthe fly's eye lens 5 and on the plane conjugate with the entrance planecan also be called pupil luminance distributions.

The condenser optical system 6 condenses beams of light emitted from thefly's eye lens 5 and thereafter the condensed beams illuminate theillumination field stop 7 in a superimposed manner. The light from theillumination field stop 7 travels through the field stop imaging opticalsystem 8 to reach the mask M with the predetermined pattern thereon andto form an illumination region as an image of an aperture of theillumination field stop 7 in at least a part of the pattern-formedregion of the mask M. FIG. 1 is depicted without any path bending mirrorfor bending the optical axis AX, but it is possible to arrange a pathbending mirror or path bending mirrors as occasion may demand. The maskM is mounted on the mask stage MS.

The projection optical system PL forms an image of the first surface ona projection surface (second surface) Wa of the wafer W mounted on thewafer stage WS, based on light from the illumination region formed onthe pattern surface (first surface) of the mask M by the illuminationapparatus IL.

In this manner, one-shot exposure or scan exposure is carried out whiletwo-dimensionally driving and controlling the wafer stage WS and,therefore, two-dimensionally driving and controlling the wafer W, in theplane (X-Y plane) perpendicular to the optical axis AX of the projectionoptical system PL. This causes the pattern of the mask M to besequentially transferred into each of exposure areas on the wafer W.

The configuration of the spatial light modulation unit 3 will bedescribed below with reference to FIGS. 2 and 3. FIG. 2 is an opticalpath diagram showing the spatial light modulation unit 3 and zoomoptical system 4 shown in FIG. 1. FIG. 3A is a partial perspective viewof the spatial light modulator 3 a in the spatial light modulation unit3, FIG. 3B is a drawing for explaining parameters for control on thepostures of the mirror elements, FIG. 3C is a partial perspective viewshowing one of the mirror elements in the spatial light modulator 3 a,and FIG. 3D is a drawing showing a cross section along line I-I of themirror element shown in FIG. 3C. It is noted that FIGS. 2 and 3 aredepicted without hatching for sections, for easier viewing.

As shown in FIG. 2, the spatial light modulation unit 3 has a prism 3 b,and the reflective spatial light modulator 3 a attached integrally tothe prism 3 b. The prism 3 b is made of a glass material, e.g.,fluorite. The prism 3 b is of a shape in which one side face of arectangular parallelepiped is depressed in a V-shaped wedge form, and isalso called a K prism. In the prism 3 b, one side face of therectangular parallelepiped part is composed of two planes PS1, PS2(first and second planes PS1, PS2) intersecting at an obtuse angle as anintersecting line (straight line) P1 a between them subsides inside. Thespatial light modulator 3 a is attached onto a side face of the prism 3b facing both of these two side faces in contact at the intersectingline P1 a. The optical material forming the base of the spatial lightmodulator 3 a is not limited to fluorite, but it may be silica glass orother optical glass.

The two side faces (the sides facing each other) in contact at theintersecting line P1 a function as first and second reflecting surfacesR11, R12. Therefore, the first reflecting surface R11 is located on thefirst plane PS1. The second reflecting surface R12 is located on thesecond plane PS2 intersecting with the first plane PS1. The anglebetween the first and second reflecting surfaces R11, R12 is an obtuseangle.

The angles herein may be determined, for example, as follows: the anglebetween the first and second reflecting surfaces R11, R12 is 120°; theangle between the side face (entrance plane IP) of the prism P1perpendicular to the optical axis AX, and the first reflecting surfaceR11 is 60°; the angle between the side face (exit plane OP) of the prismP1 perpendicular to the optical axis AX, and the second reflectingsurface R12 is 60°.

The prism 3 b is so arranged that the side face to which the spatiallight modulator 3 a is attached is parallel to the optical axis AX, thatthe first reflecting surface R11 is located on the light source 1 side(upstream in the exposure apparatus EA), and that the second reflectingsurface R12 is located on the fly's eye lens 5 side (downstream in theexposure apparatus EA). Therefore, the first reflecting surface R11 ofthe prism 3 b is obliquely arranged with respect to the optical axis AXof the exposure apparatus EA, as shown in FIG. 2. The second reflectingsurface R12 of the prism 3 b is also obliquely arranged with an oppositeinclination to the first reflecting surface R11 with respect to theoptical axis AX of the exposure apparatus EA, as shown in FIG. 2.

The first reflecting surface R11 of the prism 3 b reflects lightincident in parallel with the optical axis AX of the exposure apparatusEA. The spatial light modulator 3 a is arranged in the optical pathbetween the first reflecting surface R11 and the second reflectingsurface R12 and reflects the light reflected on the first reflectingsurface R11. The second reflecting surface R12 of the prism 3 b reflectsthe light reflected on the spatial light modulator 3 a. This light fromthe reflecting surface R12 is emitted, specifically, into the zoomoptical system 4 in the illumination apparatus IL of the exposureapparatus EA.

Therefore, the intersecting line P1 a being a ridge line formed by thefirst and second planes PS1, PS2 is located on the spatial lightmodulator 3 a side with respect to the first and second reflectingsurfaces R11, R12.

The prism 3 b in this embodiment is integrally formed of one opticalblock, but the prism 3 b may be constructed using a plurality of opticalblocks.

The spatial light modulator 3 a applies spatial modulation to theincident light, according to a position where the light reflected on thefirst reflecting surface R11 is incident. This spatial light modulator 3a, as described below, includes a large number of microscopic mirrorelements SE1 arranged two-dimensionally on a predetermined plane.

For this reason, the light beam incident to the spatial light modulator3 a travels, for example, as follows: a ray L1 impinges upon a mirrorelement SE1 a out of the plurality of mirror elements SE1 of the spatiallight modulator 3 a ; a ray L2 impinges upon a mirror element SE1 bdifferent from the mirror element SE1 a out of the plurality of mirrorelements SE1 of the spatial light modulator 3 a ; a ray L3 impinges upona mirror element SE1 c different from the mirror elements SE1 a, SE1 bout of the plurality of mirror elements SE1 of the spatial lightmodulator 3 a ; a ray L4 impinges upon a mirror element SE1 d differentfrom the mirror elements SE1 a-SE1 c out of the plurality of mirrorelements SE1 of the spatial light modulator 3 a ; a ray L5 impinges upona mirror element SE1 e different from the mirror elements SE1 a-SE1 dout of the plurality of mirror elements SE1 of the spatial lightmodulator 3 a. The mirror elements SE1 a-SE1 e apply the spatialmodulation according to the installation position of their own to thearriving rays L1-L5, respectively. FIG. 2 is depicted with illustrationof only the five mirror elements SE1 a-SE1 e, for easier explanation,but the number of mirror elements does not have to be limited to five.

The prism 3 b is so arranged that an air-equivalent length from theentrance plane IP of the prism 3 b (where the rays L1-L5 are incident)via the mirror elements SE1 a- SE1 e to the exit plane OP of the prism 3b where the rays are outgoing, is equal to an air-equivalent length froma position corresponding to the entrance plane IP to a positioncorresponding to the exit plane OP without the prism 3 b in the exposureapparatus EA. An air-equivalent length is an optical path lengthobtained by reducing an optical path length in an optical system to onein air having the refractive index of 1, and an air-equivalent length ina medium having the refractive index n is obtained by multiplying anoptical path length therein by 1/n.

The spatial light modulator 3 a is arranged near the front focal pointof the zoom optical system 4 which can be regarded as a condensingoptical system. The light reflected by the mirror elements SE1 a-SE1 eof the spatial light modulator 3 a and provided with a predeterminedangle distribution forms a light intensity distribution at apredetermined position on the rear focal plane 5 a of the zoom opticalsystem 4. Namely, the zoom optical system 4 is a Fourier transformoptical system which converts angles given to the emerging rays by themirror elements SE1 a-SE1 e of the spatial light modulator 3 a, intopositions on the plane 5 a being the far field (Fraunhofer diffractionregion) of the spatial light modulator 3 a. The zoom optical system 4applicable herein is, for example, a zoom optical system whoseprojection is an orthogonal projection.

Referring back to FIG. 1, the entrance plane of the fly's eye lens 5 islocated near this plane Sa and the light intensity distribution(luminance distribution) of the secondary light source formed by thefly's eye lens 5 is a distribution according to the light intensitydistribution formed by the spatial light modulator 3 a and zoom opticalsystem 4.

The spatial light modulator 3 a, as shown in FIG. 3A, is a movablemulti- mirror including the mirror elements SE1 being a large number ofmicroscopic reflecting elements laid with their reflecting surface of aplanar shape up. Each mirror element SE1 is movable and inclination ofthe reflecting surface thereof, i.e., an angle and direction ofinclination of the reflecting surface, is independently controlled bythe control unit 10 (posture control of the reflecting surfaces). Eachmirror element SE1 can be continuously or discretely rotated by adesired angle of rotation around each of axes along two directionsparallel to the reflecting surface thereof and orthogonal to each other.Namely, each mirror element SE1 is so configured that the inclinationthereof can be controlled in two dimensions along the reflecting surfacethereof. In the case of discrete rotation, a preferred control method isto control the angle of rotation in multiple stages (e.g., . . . ,−2.5°, −2.0°, . . . , 0°, +0.5°, . . . , +2.5°, . . .).

The above-described posture control of the reflecting surface for eachmirror element SE1 is implemented by adjusting an angle 0 between anormal to a reference plane of the spatial light modulator 3 a (z-axis)and a normal to the reflecting surface (z′ axis), as shown in FIG. 3B.The reference plane herein is a plane coincident with the reflectingsurface before the posture control, which is an x-y plane defined by anx-axis and a y-axis orthogonal to the normal z′ to the reflectingsurface before the posture control. The angle θ between the normal z(z-axis) to the reference plane and the normal z′ to the reflectingsurface is given by a rotation angle component θ_(x) around the x-axisand a rotation angle component θ_(y) around the y-axis, as specificposture control information. Specifically, the rotation angle componentθ_(x) is an angle between the normal z to the reference plane and thenormal z′ to the reflecting surface when the normal z′ is projected ontothe y-z plane, and the rotation angle component θ_(y) is an anglebetween the normal z to the reference plane and the normal z′ to thereflecting surface when the normal z′ is projected onto the x-z plane.

In addition, the contour of the mirror elements SE1 is square in thisembodiment, but the contour is not limited to it. However, the contouris preferably a shape permitting arrangement without a gap (the closestpacking) in terms of light utilization efficiency. The gap betweenadjacent mirror elements SE1 is preferably set to a necessary minimumlevel.

FIG. 3C is a drawing schematically showing a configuration of one mirrorelement out of the plurality of mirror elements SE1 of the spatial lightmodulator 3 a and, more specifically, a drawing schematically showing adrive unit for controlling the posture of the reflecting surface in themirror element SE1. FIG. 3D is a drawing showing a cross section of themirror element SE1 along line I-I shown in FIG. 3C. In FIGS. 3C and 3D,the mirror element SE1 has a base 30, a support 31 disposed on this base30, a plate member 32 connected to the support 31 on the opposite sideto the base 30, a reflecting surface 33 consisting of a reflecting filmformed on this plate member 32, and four electrodes 34 a-34 d arrangedso as to surround the support 31 on the base 30.

The plate member 32 is inclinable around two axes (x-axis and y-axis)orthogonal to each other on a plane parallel to the base 30 with afulcrum at a joint to the support 31. Then potentials are given to theelectrodes 34 a-34 d arranged at respective positions on the base sidecorresponding to the four corners of the plate member 32, to generate anelectrostatic force between each electrode 34 a-34 d and the platemember 32, thereby varying the gap between each electrode 34 a-34 d andthe plate member 32 (drive unit). This causes the plate member 32 to beinclined on the fulcrum of the support 31 and, therefore, the reflectingsurface 33 formed on the plate member 32 is inclined.

Now, multilevel control of the light intensity distribution (pupilluminance distribution) formed on the illumination pupil plane will beexplained referring back to FIG. 2. In the state of the spatial lightmodulator 3 a shown in FIG. 2, the mirror elements are arranged asfollows: among the five mirror elements SE1 a-SE1 e, each of the threemirror elements SE1 a, SE1 c, SE1 e is inclined by a first angle(θ_(x1), θ_(y1)) with respect to the reference plane of the spatiallight modulator 3 a ; each of the two mirror elements SE1 b, SE1 d isinclined by a second angle (θ_(x2), θ_(y2)) different from the firstangle with respect to the reference plane of the spatial light modulator3 a.

Accordingly, the reference plane of the spatial light modulator 3 a (cf.FIG. 3B) means a plane in which the large number of mirror elements SE1of the spatial light modulator 3 a are two-dimensionally arranged. Thefirst angle and second angle are defined using rotation directionsθ_(x), θ_(y) around the rotation axes of two axes (x-axis and y-axis)orthogonal in the foregoing plane, as shown in FIG. 3B.

The rays L1, L3, L5 reflected on the three mirror elements SE1 a, SE1 c,SE1 e of the spatial light modulator 3 a are reflected on the secondreflecting surface R12 of the prism 3 b and thereafter are condensed bythe zoom optical system 4. As a consequence, the rays L1, L3, L5 arriveat a point P1 on the rear focal plane Sa of the zoom optical system 4.On the other hand, the rays L2, L4 reflected on the two mirror elementsSE1 b, SE1 d of the spatial light modulator 3 a are reflected on thesecond reflecting surface R12 of the prism 3 b and thereafter arecondensed by the zoom optical system 4. As a consequence, the rays L2,L4 arrive at a point P2 on the rear focal plane 5 a of the zoom opticalsystem 4.

In this manner, the rays from the three mirror elements SE1 a, SE1 c,SE1 e are focused at the point P1, while the rays from the two mirrorelements SE1 b, SE1 d are focused at the point P2. As a result, a ratioof the light intensity at the point P1 to the light intensity at thepoint P2 is 3:2. Based on such relationship between the numbers ofmirror elements and the light intensity ratio, the light intensity at apredetermined point (P1 or P2) is determined according to the number ofreflecting surfaces (SE1 a, SE1 c, SE1 e or SE1 b, SE1 d) contributingto rays (L1, L3, L5 or L2, L4) arriving at the predetermined point (P1or P2) on the rear focal plane 5 a of the zoom optical system 4 whichcan be regarded as the illumination pupil plane. Namely, the lightintensity distribution on the plane 5 a can be controlled to a desireddistribution. In the configuration example shown in FIG. 2, the lightintensity distribution (pupil luminance distribution) formed on theplane 5 a is one in which the light intensity at the point P1 is 3, thelight intensity at the point P2 is 2, and the light intensity in theother region is 0.

Therefore, when the control unit 10 (cf. FIG. 1) to perform the posturecontrol in the spatial light modulator 3 a is configured to control thenumber of reflecting surfaces contributing to arriving light, for eachpoint (e.g., P1 or P2) forming the light intensity distribution formedon the plane 5 a, the light intensity at the predetermined point (P1 orP2) on the plane 5 a can be set at a desired value and, in turn, thelight intensity distribution on the plane 5 a can be optionallycontrolled on a multilevel basis.

Since in this embodiment the zoom optical system 4 has the opticalFourier transform action, the rays are superimposed at one point P1 onthe rear focal plane 5 a of the zoom optical system 4 even though theinclinations of the three mirror elements SE1 a, SE1 c, SE1 e are thesame first angle (θ_(x1), θ_(y1)); and the rays are also superimposed atone point P2 on the rear focal plane 5 a of the zoom optical system 4even though the inclinations of the two mirror elements SE1 b, SE1 d arethe same second angle (θ_(x2), θ_(y2)). In this embodiment, as describedabove, the inclinations of the reflecting surfaces contributing to lightarriving at a certain point on the plane 5 a are controlled not todifferent inclinations, but to the same inclination (the same posture).

In this embodiment, the angle information of light caused byinclinations of the mirror elements SE1 of the spatial light modulator 3a is converted into position information on the plane 5 a being aFourier transform plane, by the optical Fourier transform action of thezoom optical system 4. Conversely, angle information of light on theFourier transform plane 5 a is converted into position information onthe arrangement plane of the mirror elements SE1 of the spatial lightmodulator 3 a. As a result, the divergence angle (NA) of beams reachingthe plane 5 a which can be regarded as the illumination pupil plane iseffectively prevented from varying in the plane 5 a. In addition,selection of settings of mirror elements and inclinations thereof can bedone without any restrictions on which mirror element SE1 should be setat which inclination out of the plurality of mirror elements SE1, forsetting the light intensity distribution (pupil luminance distribution)formed on the plane 5 a, to a desired distribution.

For example, it is also possible to adopt a method of grouping theplurality of mirror elements SE1 of the spatial light modulator 3 a intoa plurality of mirror element groups 35 a-35 i and letting the mirrorelement groups 35 a-35 i form their respective light intensitydistributions (pupil luminance distributions) on the plane 5 a, as shownin FIG. 4. It is also possible to adopt another method of assigning theplurality of mirror elements SE1 of the spatial light modulator 3 acompletely at random.

FIGS. 5A and 5B are drawings for schematically explaining anotherexample of the method for multilevel control of the pupil intensitydistribution. Specifically, FIG. 5A is a matrix showing an example ofthe light intensity distribution (pupil intensity distribution) of4-valued expression where the illumination pupil plane is composed of 15pixels in 3 rows×5 columns, and FIG. 5B is a drawing for schematicallyexplaining assignment of light necessary for obtaining the multilevellight intensity distribution shown in FIG. 5A.

For example, for obtaining the light intensity of the leftmost bottompixel on the matrix shown in FIG. 5A, light energies PE1-PE4 from fourmirror elements of the spatial light modulator 3 a are superimposed onthe leftmost bottom pixel to obtain intensity 4, as shown in FIG. 5B.Similarly, for obtaining the light intensity of the leftmost top pixelon the matrix shown in FIG. 5A, light energies PE5, PE6 from two mirrorelements of the spatial light modulator 3 a are superimposed on theleftmost top pixel to obtain intensity 2, as shown FIG. 5B.

In this manner, it becomes feasible to control the value of lightintensity at a predetermined point on the plane 5 a in multiple levels(four levels in the case of FIGS. 5A and 5B), by controlling the numberof reflecting surfaces contributing to light arriving at thepredetermined point on the plane 5 a.

The example shown in FIGS. 5A and 5B showed the division of 15 pixels of3×5 pixels for the illumination pupil plane in order to simplify thedescription, but the number of divisions of the illumination pupil planedoes not have to be limited to 15, and may be a larger number ofdivisions, e.g., 40×40 pixels, 128×128 pixels, and so on. Furthermore,the example shown in FIGS. 5A and 5B showed the multilevel expression ofthe light intensity distribution formed on the illumination pupil plane,based on the multiple values of four levels, but the multilevels do nothave to be limited to the four levels, and can be any of various numbersof levels according to need, e.g., three levels, eight levels, and soon.

When the total number of reflecting surfaces necessary for formation ofthe desired light intensity distribution on the illumination pupil planeis not equal to the total number of mirror elements SE1 of the spatiallight modulator 3 a illuminated with the light from the light source 1(which will be referred to hereinafter as an effective number of mirrorelements), specifically, when there is a remainder when the effectivenumber of mirror elements is divided by the total number of reflectingsurfaces necessary for formation of the pupil intensity distribution onthe illumination pupil plane, it is preferable that the light reflectedon the remaining reflecting surfaces be directed to the region otherthan the illumination pupil plane.

When the light reflected on the remaining reflecting surfaces isaveragely scattered over the light intensity distribution formed on theillumination pupil plane, intensity unevenness will occur in this lightintensity distribution. For example, let the effective number of mirrorelements be 169760 and the total number of reflecting surfaces necessaryfor formation of the light intensity distribution be 12861; then theremainder is 2567. Namely, the number of mirror elements regarded as onereflecting surface is 13 (169760=12861×13+2567) and light reflected fromthese thirteen mirror elements arrives at one point on the illuminationpupil plane.

Let us suppose that the illumination pupil plane is divided in 128×128pixels and that reflected light from the remaining mirror elements isalso guided to any of pixels forming the effective pupil constitutingthe light intensity distribution. In this case there are pixels at whichreflected light from thirteen mirror elements arrives and pixels atwhich reflected light from fourteen mirror elements arrives, in theeffective pupil. In this example, the intensity unevenness of the lightintensity distribution formed on the illumination pupil plane is givenby |(14−13)/(14+13)|=|1/27|, or ±3.7% (=±(1/27)×100). On the other hand,since the rate of the remainder to the effective number of mirrorelements is 1.5% (=(2567/169760)×100), a reduction in illuminance on theentire effective pupil is just 1.5% even in the case where the reflectedlight from the 2567 remaining mirror elements is guided to the outsideregion of the effective pupil. Therefore, when the reflected light fromthe 2567 remaining mirror elements is intentionally guided to the regionother than the effective region, the intensity unevenness of the lightintensity distribution formed on the illumination pupil plane can bereduced by 3.7%.

In the above embodiment, the spatial light modulator with the pluralityof optical elements arranged two-dimensionally and controlledindividually had the structure in which each optical element wassupported so as to be inclinable on a fulcrum at one support in thecenter thereof. However, it is also possible to adopt a structure inwhich each of the optical elements in the spatial light modulator issupported in the peripheral region.

In the above embodiment, the spatial light modulator in which theorientations (inclinations) of the reflecting surfaces arrangedtwo-dimensionally can be individually controlled is used as the spatiallight modulator with the plurality of optical elements arrangedtwo-dimensionally and controlled individually. However, without havingto be limited to this, it is also possible, for example, to use aspatial light modulator in which heights (positions) of the reflectingsurfaces arranged two-dimensionally can be individually controlled. Sucha spatial light modulator applicable herein is, for example, oneselected from those disclosed in Japanese Patent Application Laid-openNo. 6-281869 and U.S. Pat. No. 5,312,513 corresponding thereto, and inFIG. 1d of Japanese Patent Application Laid-open (Translation of PCTApplication) No. 2004-520618 and U.S. Pat. No. 6,885,493 correspondingthereto. The teachings of the U.S. Pat. Nos. 5,312,513 and 6,885,493 areincorporated by reference. These spatial light modulators are able toapply the same action as a diffracting surface, to incident light byforming a two-dimensional height distribution therein. In this case, thecontrol unit may be configured to control the number of depressions andprojections of the reflecting surfaces in the spatial light modulator(the posture control of the reflecting surfaces in the spatial lightmodulator by the control unit).

The aforementioned spatial light modulator with the plurality ofreflecting surfaces arranged two-dimensionally may be modified, forexample, according to the disclosure in Japanese Patent ApplicationLaid-open (Translation of PCT Application) No. 2006-513442 and U.S. Pat.No. 6,891,655 corresponding thereto, or according to the disclosure inJapanese Patent Application Laid-open (Translation of PCT Application)No. 2005-524112 and U.S. Patent Published Application No. 2005/0095749corresponding thereto. The teachings of the U.S. Pat. No. 6,891,655 andthe U.S. Patent Published Application No. 2005/0095749 are incorporatedby reference.

In the above-described embodiment and modification examples, theapparatus may be modified so that in the formation of the lightintensity distribution (pupil luminance distribution) on theillumination pupil plane using the spatial light modulator 3, the lightintensity distribution formed is measured with a light intensitydistribution measuring device (pupil luminance distribution measuringdevice) and the spatial light modulator 3 is controlled according to theresult of the measurement. Such technology is disclosed, for example, inJapanese Patent Application Laid-open No. 2006-54328 and in JapanesePatent Application Laid-open No. 2003-22967 and U.S. Patent PublishedApplication No. 2003/0038225 corresponding thereto. The teachings of theU.S. Patent Published Application No. 2003/0038225 are incorporated byreference.

In the aforementioned embodiment, the mask can be replaced with avariable pattern forming device which forms a predetermined pattern onthe basis of predetermined electronic data. The variable pattern formingdevice applicable herein is, for example, a spatial light modulatorincluding a plurality of reflecting elements driven based onpredetermined electronic data. The exposure apparatus with such aspatial light modulator is disclosed, for example, in Japanese PatentApplication Laid-open No. 2004-304135 and International Publication WO2006/080285 and U.S. Pat. Published Application No. 2007/0296936corresponding thereto. The teachings of the U.S. Pat. PublishedApplication No. 2007/0296936 are incorporated by reference. Besides thereflective spatial light modulators of the non-emission type, it is alsopossible to use a transmissive spatial light modulator or aself-emission type image display device.

In the foregoing embodiment, it is also possible to apply a technique offilling the interior of the optical path between the projection opticalsystem and the photosensitive substrate with a medium having therefractive index larger than 1.1 (typically, a liquid), which is socalled a liquid immersion method. In this case, it is possible to adoptone of the following techniques as a technique of filling the interiorof the optical path between the projection optical system and thephotosensitive substrate with the liquid: the technique of locallyfilling the optical path with the liquid as disclosed in InternationalPublication WO99/49504; the technique of moving a stage holding thesubstrate to be exposed, in a liquid bath as disclosed in JapanesePatent Application Laid-open No. 6-124873; the technique of forming aliquid bath of a predetermined depth on a stage and holding thesubstrate therein as disclosed in Japanese Patent Application Laid-openNo. 10-303114, and so on. The teachings of the International PublicationWO99/49504, and the Japanese Patent Application Laid-open Nos. 6-124873and 10-303114 are incorporated by reference.

The exposure apparatus of the foregoing embodiment is manufactured byassembling various sub-systems containing their respective components asset forth in the scope of claims in the present application, so as tomaintain predetermined mechanical accuracy, electrical accuracy, andoptical accuracy. For ensuring these various accuracies, the followingadjustments are carried out before and after the assembling: adjustmentfor achieving the optical accuracy for various optical systems;adjustment for achieving the mechanical accuracy for various mechanicalsystems; adjustment for achieving the electrical accuracy for variouselectrical systems. The assembling blocks from the various sub-systemsinto the exposure apparatus include mechanical connections, wireconnections of electric circuits, pipe connections of pneumaticcircuits, etc. between the various sub-systems. It is needless tomention that there are assembling blocks of the individual sub-systems,before the assembling blocks from the various sub-systems into theexposure apparatus. After completion of the assembling blocks from thevarious sub-systems into the exposure apparatus, overall adjustment iscarried out to ensure various accuracies as the entire exposureapparatus. The manufacture of exposure apparatus is desirably performedin a clean room in which the temperature, cleanliness, etc. arecontrolled.

The following will describe a device manufacturing method using theexposure apparatus according to the above-described embodiment. FIG. 6is a flowchart for explaining manufacturing blocks of semiconductordevices, as the device manufacturing method according to an embodimentof the present invention. As shown in FIG. 6, the manufacturing blocksof semiconductor devices include depositing a metal film on a wafer W tobecome a substrate of semiconductor devices (block S40) and applying aphotoresist as a photosensitive material onto the deposited metal film(block S42). The subsequent blocks include transferring a pattern formedon a mask (reticle) M, into each shot area on the wafer W, using theexposure apparatus (projection exposure apparatus) of the foregoingembodiment (block S44: exposure block), and developing the wafer W aftercompletion of the transfer, i.e., developing the photoresist to whichthe pattern has been transferred (block S46: development block).Thereafter, using the resist pattern made on the surface of the wafer Win block S46, as a mask, processing such as etching is carried out onthe surface of the wafer W (block S48: processing block).

The resist pattern herein is a photoresist layer in which depressionsand projections are formed in a shape corresponding to the patterntransferred by the projection exposure apparatus of the foregoingembodiment and which the depressions penetrate throughout. Step S48 isto process the surface of the wafer W through this resist pattern. Theprocessing carried out in block S48 includes, for example, at leasteither etching of the surface of the wafer W or deposition of a metalfilm or the like. In block S44, the projection exposure apparatus of theforegoing embodiment performs the transfer of the pattern onto the waferW coated with the photoresist, as a photosensitive substrate or plate P.

FIG. 7 is a flowchart for explaining manufacturing blocks of a liquidcrystal device such as a liquid-crystal display device, as the devicemanufacturing method according to another embodiment of the presentinvention. As shown in FIG. 7, the manufacturing blocks of the liquidcrystal device include sequentially performing a pattern forming block(block S50), a color filter forming block (block S52), a cell assemblyblock (block S54), and a module assembly block (block S56).

The pattern forming block of block S50 is to form predetermined patternssuch as a circuit pattern and an electrode pattern on a glass substratecoated with a photoresist, as a plate P, using the projection exposureapparatus of the foregoing embodiment. This pattern forming blockincludes an exposure block of transferring a pattern to a photoresistlayer, using the aforementioned projection exposure apparatus, adevelopment block of performing development of the plate P onto whichthe pattern has been transferred, i.e., development of the photoresistlayer on the glass substrate, and then making the photoresist layer inthe shape corresponding to the pattern, and a processing block ofprocessing the surface of the glass substrate through the developedphotoresist layer.

The color filter forming block of block S52 is to form a color filter inwhich a large number of sets of three dots corresponding to R (Red), G(Green), and B (Blue) are arrayed in a matrix pattern, or in which aplurality of filter sets of three stripes of R, G, and B are arrayed ina horizontal scan direction.

The cell assembly block of block S54 is to assemble a liquid crystalpanel (liquid crystal cell), using the glass substrate on which thepredetermined pattern has been formed in block S50, and the color filterformed in block S52. Specifically, for example, a liquid crystal ispoured into between the glass substrate and the color filter to form theliquid crystal panel. The module assembly block of block S56 is toattach various components such as electric circuits and backlights fordisplay operation of this liquid crystal panel, to the liquid crystalpanel assembled in block S54.

An embodiment of the present invention is not limited only to theapplication to the exposure apparatus for manufacture of semiconductordevices, but can also be widely applied, for example, to the exposureapparatus for the liquid-crystal display devices formed with rectangularglass plates, or for display devices such as plasma displays, and to theexposure apparatus for manufacture of various devices such as imagingdevices (CCDs and others), micromachines, thin-film magnetic heads, andDNA chips. Furthermore, an embodiment of the present invention is alsoapplicable to the exposure block (exposure apparatus) for manufacture ofmasks (photomasks, reticles, etc.) with mask patterns of various devicesthereon, by the photolithography process.

In the above-described embodiment, the light (exposure light) suppliedby the light source 1 can be an ArF excimer laser light (wavelength: 193nm) or a KrF excimer laser light (wavelength: 248 nm). However, withouthaving to be limited to this, it is also possible to use any otherappropriate laser light source, e.g., an F₂ laser light source whichsupplies laser light at the wavelength of 157 nm.

The aforementioned embodiment was the application of the presentinvention to the illumination optical system illuminating the mask inthe exposure apparatus, but, without having to be limited to this, anembodiment of the present invention can also be applied to agenerally-used illumination optical system which illuminates anillumination target surface except for the mask.

As described above, an embodiment of the present invention successfullyprovides the multilevel pupil luminance distribution (pupil intensitydistribution) in which luminances in respective zones are optionallycontrolled.

As described above, the present invention can be modified in variousways without departing from the scope and spirit of the presentinvention, without having to be limited to the above embodiments.

What is claimed is:
 1. An illumination apparatus which illuminates anillumination target surface with light from a light source, theillumination apparatus comprising: a spatial light modulator with aplurality of reflecting surfaces arranged two- dimensionally, posturesof the respective reflecting surfaces being controlled independently ofeach other; a first condensing optical system configured to condenselight from the plurality of reflecting surfaces of the spatial lightmodulator onto a predetermined surface in an optical path of theillumination apparatus; a fly's eye optical system with a plurality ofoptical surfaces arranged two- dimensionally on the predeterminedsurface, configured to form a light intensity distribution on anillumination pupil plane by light from the first condensing opticalsystem; and a controller configured to control the plurality ofreflecting surfaces of the spatial light modulator, wherein thecontroller controls postures of the plurality of reflecting surfaces sothat light from a first reflecting surface and light from a secondreflecting surface different from the first reflecting surface overlapon the predetermined surface after passing through the first condensingoptical system, both the first and second reflecting surfaces beingincluded in the plurality of reflecting surfaces.